Chapter 12 Part 1 Flashcards
the nervous system includes all the _____ of the body
neural tissue
what are the basic functional units of the nervous system?
neurons
what is the function of neuroglia? what is another word for them?
neuroglia are supporting cells, essential to the survival and functionality of neurons AND to preserving the physical and biochemical structure of neural tissue
another name for them = glial cells
which are there more of — neurons or neuroglia?
neuroglia FAR outnumber neurons
what are the organs of the nervous system?
-the brain and spinal cord
-the receptors in “complex sense organs” (the ear and eye)
-the nerves that link the nervous system with other systems
viewed ANATOMICALLY, the nervous system has _____ divisions:
2 divisions:
the CNS (central nervous system) and
the PNS (peripheral nervous system)
what does the CNS consist of?
the brain and spinal cord
the brain and spinal cord are complex organs that include….
-neural tissue
-blood vessels
-various connective tissue
What is the function of the connective tissues in the brain and spinal cord
physical protection and support
What is the CNS responsible for?
integrating, processing, and coordinating sensory data and motor commands
Sensory data convey information about what?
conditions inside or outside of the body
what do motor commands do?
control or adjust the activities of peripheral organs (such as skeletal muscle)
what is the seat of higher functions, such as intelligence, memory, learning, and emotion?options: CNS or PNS
CNS – specifically the brain
Explain what is happening with the CNS when we stumble
when we stumble, the CNS integrates information about your balance and the position of your limbs and then COORDINATES your recovery by sending motor commands to appropriate skeletal muscles
When we stumble and the CNS coordinates our recovery, is this done with your own conscious effort?
no — happens in a split second without our conscious effort
the PNS includes……
all of the neural tissue outside of the CNS
What is the function of the PNS?
the PNS:
- delivers sensory information to the CNS
- carries out motor commands to peripheral tissues and systems
What actually carries the sensory information and motor commands in the PNS?
bundles of axons — called nerve fibers
these bundles of axons (nerve fibers) are called _________ when they’re associated with blood vessels or connective tissue
peripheral nerves —- or simply nerves
nerves connected to the brain are called …..
cranial nerves
nerves attached to the spinal cord are called….
spinal nerves
describe the 2 basic functional divisions of the PNS
the PNS can be divided into afferent and efferent divisions
the afferent division brings sensory information TO the CNS FROM receptors in peripheral tissues and organs
the efferent division carries motor commands FROM the CNS to muscles, glands, and adipose tissue
the efferent division of the PNS carries motor commands from the CNS to muscles, glands, and adipose tissue.
What is the term for these target organs?
effectors
what are receptors? what division of the nervous system are they associated with?
receptors are SENSORY STRUCTURES that either detect changes in the environment (internal or external) OR respond to specific stimuli
they are associated with the AFFERENT division of the PNS – gives info TO THE CNS
Our receptors range from ____ to _____
slender, cytoplasmic extensions of single cells to complex receptor organs (such as the eye and ear)
Receptors are either ____ or ______ in other tissues
receptors are either NEURONS or SPECIALIZED CELLS in other tissues
divide the PNS further (not just afferent and efferent divisions)
the efferent division of the PNS can be divided into the…
SNS (somatic nervous system)
ANS (autonomic nervous system)
ANS can be divided into a sympathetic division and a parasympathetic division
what is the function of the SNS and what division of the PNS does it belong to
the SNS belongs to the EFFERENT division of the PNS
the function of the SNS is to control skeletal muscle contractions.
Are skeletal muscle contractions voluntary or involuntary? explain
skeletal muscle contractions can be voluntary or involuntary
voluntary = conscious control. ie: raising your hand
involuntary = an automatic response called a REFLEX. ie: putting your hand on a hot stove and immediately removing it BEFORE WE EVEN NOTICE ANY PAIN
Describe the function of the ANS and what division of the nervous system it belongs to
ANS = autonomic nervous system.
belongs to the efferent division of the PNS
the ANS provides AUTOMATIC regulation of smooth muscle, cardiac muscle, glandular secretions, and adipose tissue, (at the subconscious level)
the ANS can further be divided into….
the sympathetic division and the parasympathetic division
the parasympathetic and sympathetic divisions of the ANS have ___ functions. explain
antagonistic
for example, the sympathetic division accelerates the heart rate, whereas the parasympathetic slows it down
What is the most common type of neuron in the CNS? describe its structure
the most common type of neuron in the CNS is the multipolar neuron.
multipolar neuron structure:
large cell body, several short, branched dendrites, and a single long axon ending in terminal branches called telodendria
what is another word for the cell body
soma
the cell body contains….
a large, round nucleus with a prominent nucleolus
what is the perikaryon?
the cytoplasm surrounding the nucleus of the cell body
do neurons have a cytoskeleton?
yes
the cytoskeleton of the perikaryon contains….
neurofilaments
neurotubules
neurofilaments are similar to the _____ of other types of cells
neurotubules are similar to the ____ of other types of cells
neurofilaments ~ intermediate filaments
neurotubules ~ microtubules
what are bundles of neurofilaments called?
neurofibrils
where do neurofibrils extend to?
neurofibrils extend into the dendrites and axon, which provides internal support for them
____ extend into the dendrites and axon, providing internal support for them
neurofibrils (bundles of neurofilaments)
does the perikaryon of a neuron contain organelles?
(perikaryon = cytoplasm of a neuron)
YES
What is the function of the organelles in the perikaryon of the nucleus?
the organelles provide energy and synthesize organic materials ESPECIALLY chemical neurotransmitters that are responsible for cell to cell communication
what give the perikaryon a coarse, grainy appearance?
-the numerous mitochondria
-free or fixed ribosomes
-membranes of the rough ER
do neurons have a low energy demand?
no – they have a high energy demand.
this is why they have numerous mitochondria to generate ATP to meet these demands
what structure(s) in the neuron synthesize proteins?
the ribosomes and rough ER
what are Nissl bodies?
areas of the perikaryon that contain clusters of rough ER and free ribosomes.
these regions stain darkly
Nissl bodies give a ____ color to areas containing neuron cell bodies
GRAY
this gives the gray matter seen in gross dissection of the brain and spinal cord
can typical CNS neurons divide? explain
NO they cannot divide.
this is because they lack centrioles, which are important to help organize the cytoskeleton
AND they lack microtubules that move chromosomes during mitosis
can neurons be replaced if they are lost due to injury or disease?
NO – they cannot divide
Neural stem cells are only active where?
in the NOSE and in the HIPPOCAMPUS
nose – the regeneration of olfactory (smell) receptors maintains our sense of smell
hippocampus – part of the brain involved in storing memories
TRUE OR FALSE….
neural stem cells persist in the adult nervous system, but they are typically inactive except for the nose and hippocampus
true
what are the slender extensions that extend out from the cell body?
dendrites
dendrites play key roles in _____ communication
intracellular
explain how dendrites play a key role in intracellular communication
dendrites are highly branched, and each branch has processes called DENDRITIC SPINES.
In the CNS, a neuron receives information from other neurons primarily at these dendritic spines (these account for 80-90% of a neuron’s total surface area)
_______ account for about 80-90% of a neuron’s total surface area
dendritic spines
an electrical impulse is also known as……
an action potential
what is an axon?
a long, cytoplasmic process capable of propagating an action potential (electrical signal)
what is the axoplasm and what does it contain
the axoplasm is the cytoplasm of the axon.
it contains neurofibrils, neurotubules, small vesicles, lysosomes, mitochondria, and various enzymes
what surrounds the axoplasm?
the axolemma
the axolemma may either be….
exposed to the interstitial fluid OR covered by the processes of neuroglia
the BASE of an axon (closest to the neuron) is called….
the initial segment
what is between the initial segment and the body of the neuron
the axon hillock
what are collaterals?
when an axon branches along its length, producing side branches called collaterals
what do collaterals do?
collaterals enable a single neuron to communicate with several other cells
what are telodendria
fine extensions that end either the main axon trunk or any collaterals that branch off of the axon
what is another word for telotendria
terminal branches
the telodendria end at…
synaptic terminals (also called synaptic knobs)
